The invention relates to a device for hydrodynamic entanglement for preferably binder-free compaction of the fibers of a fiber web composed of natural and/or manmade fibers of any kind, consisting of
a) a first endless belt supporting the fiber web, said belt being guided under tension and reversed between a minimum of two rolls, and PA1 b) an associated needling drum with at least one nozzle beam associated therewith, mounted axially parallel thereto and extending over the working width, and PA1 c) at least one additional nozzle beam whose water jets are directed against the back of an endless belt and through said belt against the fiber web, at least for wetting the web. PA1 d) a second endless belt, likewise stretched between at least two rolls, is located opposite the first endless belt, with the tight side of said second belt being located opposite the tight side of the first endless belt and, driven in the same direction, traveling in the same direction as the first endless belt; PA1 e) the two tight sides of the endless belts are directed conically toward one another along their lengths, so that the fiber web resting on the tight side of the first endless belt is increasingly compressed between the advancing endless belts. PA1 d) a second endless belt, likewise stretched between at least two rolls, is located opposite the first endless belt, whose tight side opposite the tight side of the first endless belt is driven to rotate in the same direction as the first endless belt, PA1 e) the two tight sides of the two endless belts are directed conically toward one another along their lengths, so that the fiber web lying on the tight side of the first endless belt is increasingly compressed between the advancing endless belts, PA1 f) the second endless belt is pressed by two rolls against a return roll of the first endless belt for greater wrapping of the reversing roll by the two endless belts, and PA1 g) the nozzle beam for wetting the fiber web is directed between these two rolls against the fiber web held compressed between the two endless belts.
A device of this kind is known from WO 96/23921. It has the advantage that the voluminous fleece arriving on an endless belt for water needling is compressed between the needling drum and the belt and at the same time is wetted by a first water curtain from the nozzle beam, whose water jets initially pass through the endless belt and then through the fiber web and finally the needling drum. However, the fact that the fiber web does not remain compressed on contact with the needling drum is disadvantageous because the circular circumferential surface of the needling drum that comes in contact with one side of the fiber web is larger than the corresponding projected length of the endless belt on the other side of the fiber web. As a result, when the fiber web is compressed against the drum, a shear stress develops between the two surfaces of the fiber web, which has a negative effect on the composition of the fleece, especially in the case of thicker fleeces.
Another device of this kind is disclosed in previous patent application 196 27 256.4. In that document
In this case also, a nozzle beam is directed against the endless belt to wet the fiber web, with the fiber web compressed between the two endless belts being initially wetted before being needled on the transfer drum.
The device according to the older patent application has the advantage that the voluminous fiber web advancing between the two endless belts is slowly compressed to an increasing degree under uniform pressure from above and below without any shear stress, and is not wetted until it is firmly gripped between the two endless belts.